[FFmpeg-user] asubboost and asupercut

[Paul B Mahol]

On Fri, Nov 27, 2020 at 11:20 PM Michael Koch <astroelectronic at t-online.de>
wrote:

> Am 27.11.2020 um 22:47 schrieb Paul B Mahol:
> > On Fri, Nov 27, 2020 at 10:40 PM Michael Koch <
> astroelectronic at t-online.de>
> > wrote:
> >
> >> Am 27.11.2020 um 20:50 schrieb Paul B Mahol:
> >>> On Fri, Nov 27, 2020 at 8:24 PM Michael Koch <
> >> astroelectronic at t-online.de>
> >>> wrote:
> >>>
> >>>> Am 27.11.2020 um 19:25 schrieb Paul B Mahol:
> >>>>> On Fri, Nov 27, 2020 at 7:09 PM Michael Koch <
> >>>> astroelectronic at t-online.de>
> >>>>> wrote:
> >>>>>
> >>>>>> Hello,
> >>>>>>
> >>>>>> I have a few questions about the asubboost and asupercut filters.
> >>>>>>
> >>>>>> -- In asubboost it's not yet clear how the block diagram of the
> filter
> >>>>>> looks like. Especially the "decay" and "feedback" options are
> unclear.
> >>>>>> What's the input of the the delay line? Before or after the low pass
> >>>>>> filter? Where does the feedback go to? Before or after the lowpass
> >>>>>> filter? I have attached a sketch of a possible block diagram, but
> it's
> >>>>>> only a wild guess.
> >>>>>>
> >>>>> This filter just adds delayed sub frequencies set by cut off
> frequency
> >>>> back
> >>>>> to output. Decay sets decay of old sub echo in buffer and feedback
> sets
> >>>> how
> >>>>> much
> >>>>> new sub frequencies are added to the delay buffer.
> >>>> Sorry, I didn't understand it. I think this filter could be explained
> >>>> much better with a block diagram.
> >>>>
> >>>>
> >>>>>> -- Is it correct that the "slope" parameter effectively changes the
> >>>>>> cutoff frequency, but doesn't change the steepness (dB / octave) of
> >> the
> >>>>>> filter?
> >>>>>>
> >>>>> It changes steepness, not cutoff.
> >>>> What's the unit of the "slope" option?
> >>>>
> >>>>
> >>> 1 / octave, can be set as dB unit, eg. -20dB, 0dB or 1 is max value.
> >>>
> >>> Use mentioned mpv command for the reason, as it displays curve.
> >> The command does not work on my computer. I did download mpv.exe and run
> >> the command line. mpv exits immediately, no output, no error message.
> >> When I run mpv without any options, then a mpv window opens.
> >>
> > Make sure you run it inside power shell or cmd.exe and make sure you
> tried
> > mpv.com too.
>
> Now with mpv.com it works. But the version doesn't yet have the
> asubboost filter. With other filters it works.
>

Download the latest release version of mpv. Also note that asubbost is not
a simple IIR filter
and thus it can not really show its response.


> Michael
>
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